By combining rapid imaging and bolus injections of the paramagnetic contrast medium gadolinium-DTPA, it is possible to perform dynamic MR imaging. The diagnostic value of dynamic MR imaging was investigated in 28 patients with focal liver lesions. Malignant tumours appear hypo-intense during the early phase of the dynamic study and are better distinguished from normal liver tissue. Haemangiomas produce a typical 'fill-in phenomenon' after contrast application and achieve very high signal intensity. Focal nodular hyperplasia is characterised by very rapid signal enhancement within the first minute after contrast injection. Dynamic MR imaging represents further improvement in the MR differentiation of liver tumours.